1. Field of the Invention
The present invention relates generally to a method and apparatus for supporting mobility in a mobile broadcasting system, and in particular, to a method and apparatus for supporting mobility in a mobile broadcasting system that utilizes Electronic Service Guide (ESG).
2. Description of the Related Art
The general architecture of a Convergence of Broadcast and Mobile Services (CBMS) system is shown in FIG. 1.
As shown in FIG. 1, Internet Protocol (IP) datacast over a Digital Video Broadcasting-Handheld (DVB-H) network involves a collection of entities that work together in order to achieve the required capabilities. In FIG. 1, a Service Application (SA) 110 aggregates contents from multiple content sources and their related metadata in order to provide a particular service application. A Service Management system 120 includes several sub-systems that manage various managements for the service. A Broadcast Network 130 and an Interactive Network 135 are transmission bearers in the CBMS system. A Terminal 140 in the CBMS system receives services and signaling over the Broadcast Network 130, and communicate bidirectionally over the Interactive Network 135. In FIG. 1, the functional entities represented by reference numerals 110 to 140 are in the actual scope of the DVB-based CBMS system.
In FIG. 1, reference numerals C1 to C7 correspond to reference points, i.e., CBMS-1 to CBMS-7, between functional entities in the CBMS system, respectively. These reference numbers represent reference points in the scope of IP datacast. Among them, CBMS-1 to CBMS-4 are pointed out specifically in the DVB-based CBMS system, CBMS-5 is stated clearly up to Transmission Control Protocol/Internet Protocol (TCP/IP) in the DVB-based CBMS system, and CBMS-6 and CBMS-7 are considered for reference. In the CBMS system, transmission of Program Specific Information/Service Information (PSI/SI) information is achieved through CBMS-1, transmission of audio/video (A/V) streams and files is performed through CMBS-2, transmission of ESG metadata and point-to-multipoint (p-t-m) transmission are carried out via CBMS-3, access control to service applications, transmission of ESG metadata and point-to-point (p-t-p) transmission are performed through CBMS-4, and a p-t-p transmission service such as Short Message Service (SMS)/Multimedia Messaging Service (MMS), IP connectivity are provided through CBMS-5. Further, CBMS-6 is a reference point between the Service Management system 120 and the Broadcast Network 130, and CBMS-7 is a reference point between the Service Application 110 and the Service Management system 120. In FIG. 1, X1 to X3, which are reference points between the functional entities, represent the reference points that are outside the scope of IP datacast over DVB-H, i.e., outside the scope of the DVB-based CMBS system.
In the foregoing CBMS system, an ESG discovery mechanism of a terminal is as follows:
1) The terminal receives PSI/SI;
2) The terminal selects an IP platform;
3) The terminal retrieves an ESG bootstrap for the selected IP platform;
4) The terminal selects an ESG by the ESGProviderDiscoveryDescriptor and ESGAccessDescriptor in the ESG bootstrap; and
5) The terminal retrieves the ESG.
The ESG bootstrap includes the ESGProviderDiscoveryDescriptor and the ESGAccessDescriptor and provides the terminal with information on an ESG provider that provides an ESG in a given IP platform and how to obtain the ESG. For example, the ESG bootstrap may be provided through the Service Management system 120 of FIG. 1 in the CBMS system. The terminal then chooses an ESG it will boot based on the ESGProviderDiscoveryDescriptor and can parse a relevant ESGAccessDescriptor to boot the ESG. ESGAccessDescriptor designates acquisition information related to the ESG provider designated in the ESGProviderDiscoveryDescriptor.
The terminal first selects one IP platform, and then selects the ESG within this IP platform. The service described in the ESG may belong to one exact Internet Protocol Data Casting (IPDC) operator, and this information is given in the acquisition fragment. This means the terminal can only know which IPDC operator that each service belongs to only after the terminal selects and retrieves the ESG. Currently, the IPDC operator is identified by IPDC Key Management System ID (IPDCKMSID) and IPDCOperatorID. If the identifier is changed in the future, the related identifier should also be replaced by the new identifier. The IPDC operator can provide a broadcast service to the terminal in at least one predetermined IP platform and the ESG.
Generally, in one network, there may be multiple IP platforms. As shown in FIG. 2, each IP platform 211 has its own ESG bootstrap 220. Inside each ESG bootstrap 220, there may be multiple ESG providers (not shown), and each ESG provider may provide multiple ESGs. Each ESG describes services from a different IPDC operator 235.
In the above existing ESG acquisition method, mobility issue has not been considered. That is, as shown in FIG. 3, the terminal may select any one of its IP platform 320 in PSI/SI 310 for the ESG bootstrap, check an ESG provider based on the ESGProviderDiscoveryDescriptor in the ESG bootstrap and the ESGProviderDiscoveryDescriptor information provided from ESGAccessDescriptor, and choose an ESG 340 that the ESG provider 330 provides. After retrieving the ESG 340, the terminal acquires information on available IPDC operators 300 and chooses one possible IPDC operator.
FIG. 4 is a flowchart illustrating a general operation of a terminal for discovering an ESG. As shown in FIG. 4, the terminal acquires broadcast service information (PSI/SI) in step 405 and chooses an available IP platform in step 410. In step 415, the terminal ESG-bootstraps from the selected IP platform. The terminal chooses the ESG from the ESGProviderDiscoveryDescriptor and the ESGAccessDescriptor in step 420 and acquires the selected ESG by accessing a File Delivery over Unidirectional Transport (ESGFLUTE) session in step 425.
In step 430, the terminal determines whether it supports an available Key Management System (KMS) in the ESG. If it is determined in step 430 that it supports the available KMS, the terminal determines in step 435 whether it supports an available IPDC operator. If it is determined in step 435 that it supports an available IPDC operator, the terminal chooses one IPDC operator in step 440 and then accesses or purchases services in step 445.
However, if it is determined in step 430 that the terminal does not support the available KMS, the terminal determines in step 450 whether all the ESGs has been checked. If it is determined in step 450 that all the ESG has not been checked, the terminal determines in step 455 whether it wants to check another ESG. If it is determined in step 455 that it wants to check another ESG, the terminal proceeds to step 420; otherwise, the terminal ends the operation.
Meanwhile, if it is determined in step 450 that all the ESG has been checked, the terminal determines in step 460 whether all of the IP platform's ESG bootstrap has been checked. If it is determined in step 460 that all of the IP platform's ESG bootstrap has been checked, the terminal ends the operation. If not, the operation proceeds to step 465.
In step 465, the terminal determines whether it wants to check another ESG bootstrap from another IP platform. If it is determined in step 465 that it wants to check another ESG bootstrap, the terminal proceeds to step 410. If not, it ends the operation.
If the terminal is allowed to receive service only from a designated IPDC operator (e.g., the terminal has registered for service associated with this EPDC operator), the terminal cannot know which ESG has the service information related to the designated IPDC operator. Therefore, the terminal would need to perform the process of retrieving each ESG bootstrap's information and parsing every ESG until it finds the expected service related to its expected IPDC operator.
Especially in the roaming case, the terminal may move to a foreign area and maybe have no knowledge of which IPDC operator provides the desired service based on agreement. Therefore, according to the existing CBMS specification, the terminal would need to retrieve each and every ESG bootstrap information in order to retrieve and parse each and every ESG to search for the IPDC operator that is to provide the roaming service. Accordingly, existing ESG-related technology cannot support interactive ESG. Therefore, there is a demand for a system and method that provides interactive ESG in the interactive ESG-related technology.